With every large ship that passes the Panama Canal, sveral million cubic meters of water are needed. The Chargres Basin is the larges drainage basin providing water to the Canal zone. It is coverd mostly by primary and ecologically untouched rain forest. A multidisciplinary project involving ecologists, biologists, soil scientists, hydrologists and geologists attempts to develop a complete understanding of this reserve.

Our contribution is basic geological mapping, sampling and geochemical analysis of the rocks that form the substrate to the basin. Structural and lithological boundaries are of special importance to estimate the basement control on the drainage system and the hydrology of the basin. The basin is formed of cretaceous igneous rocks ranging in composition from altered basalts and gabbros to plagio-granites. Trace element characteristics identify a primitive island arc setting for these rocks. Radiometric dating n altered basalts and mafic andesites will be impossible. Therefore, Ar-Ar dating on amphiboles separated from the intrusive series will be attempted give a minimum age of the sequence. The Project was started in early 2002 and has not been completed.